Managing geosynchronous satellite longitudinal drift is an on-going problem. For the same ΔV, ion thrusters must be fired for a much longer duration than chemical thrusters. That duration may include several shorter firings, however, due either to electric power limitations or the desire to limit long-arc ΔV losses, or both. Thus, there may be one or more small-ΔV ion thruster firings each day over several days in order to exert station keeping longitude/drift control.
What is needed is a way to provide longitude/drift control programs for tracking two-phase geosynchronous station keeping target cycles with low thrust, high specific impulse ion thrusters.